Chancellor Angela Merkel's spokesman, Steffen Seibert, said that Merkel viewed an international response to the gas attack as inevitable.
“The gas attack is a turning point in the already lengthy internal conflict,” he said. “The Syrian government cannot hope to continue this kind of illegal warfare and go unpunished.”
But later on Thursday Merkel and Russian president Vladimir Putin agreed on the need for the UN Security Council to study a report by UN experts on the alleged chemical attack outside Damascus, the Kremlin said.
In Berlin, Seibert confirmed the telephone conversation, saying Putin and Merkel agreed that the "conflict can only be resolved politically".
The German chancellor "emphasised that the inhumane poison gas attack against Syrian civilians requires an international reaction," Seibert added.
The conversation comes as Russia is expected to veto any attempts to win UN Security Council backing for Western-led military action against the regime of
President Bashar al-Assad over last week's attack, which activists say killed hundreds of people.
Seibert said that Merkel, who will fight for a third term in elections on September 22nd, had told Putin that discussions at the UN Security Council should lead to a "unanimous and quick international reaction".
Germans against military strikes
Meanwhile, a poll released on Thursday showed that most Germans would oppose military action by the West in Syria.
Fifty-eight percent of those asked said they would reject a military response, while 33 percent said they would back it, according to the survey for ZDF public television which said nine percent were undecided.
If military action led by the United States did go ahead, 41 percent said they believed Germany should contribute financially and with equipment, compared to 55 percent who disagreed.
The phone survey was carried out from Monday to Wednesday among 1,348 people.
With the debate over whether the West should intervene in Syria intensifying, Merkel spoke with British Prime Minister David Cameron on the phone on Wednesday night, while Defence Minister Thomas de Maizière spoke with his US counterpart Chuck Hagel.
But with the USA, UK and France reportedly preparing for a military strike against Syria, the German government would not be drawn on what, if any, role it would play.
Merkel has continually stressed that she wants to see a political resolution to the conflict and is cautious of involving Germany's armed forces in any military action.
Britain moved to introduce a discussion on the matter at the United Nations Security Council on Wednesday but a meeting ended without touching the subject.
Referring to Merkel's conversation with Cameron, Seibert said: "Both hope that no member of the United Nations Security Council will close their eyes to this crime against humanity."
He said they both saw the "extensive use of poison gas against the Syrian civilian population" as proven, although UN inspectors have not yet reported on their work.
Syrian refugees welcome
Merkel also called for Germans to welcome the thousands of Syrians who are expected to be granted refuge in the country as they flee violence at home.
Germany agreed earlier this year to accept 5,000 more Syrian people, which would bring the total given refuge since the start of last year, to around 13,000.
"I ask people in Germany to welcome them here since everyone knows what they have been through," Merkel told newspaper the Mittelbayerische Zeitung in an interview.
"Germany is standing by the refugees as best it can," she said. Her comments come in the wake of a wave of xenophobia sentiment across Germany, focused in places where refugees are being housed.
Last week riot police were called to separate neo-Nazis and anti-fascists near a asylum-seekers' centre in Berlin.